In recent years, broadcast stations of FM broadcast or the like often provide information concerning programs sent from their stations and songs broadcasted in the programs via the Internet. Hence, recent audio devices having a function to receive radio waves have been being provided with an Internet connection function, considering a service of allowing information related to broadcasted songs and the like to be obtained via the Internet by the audio devices. According to the service, when a user finds a favorite song among broadcasted songs while receiving an FM broadcast, the user can access the server which provides information, and can receive and display information related to the song on a display of the audio device. It is also possible to store the received related information.
Meanwhile, audio devices can receive a radio broadcast by tuning the reception frequency to a specific value. To facilitate this operation, recent audio devices have plural preset receivable frequencies, so that the audio device can be tuned by merely specifying a number through a button operation. Further, several audio devices have a function to set automatically receivable frequencies as described above.
To utilize such an information providing service as described above, it is necessary to specify a server or web page which provides information for broadcast stations corresponding to the preset receivable frequencies. Further, receivable areas of broadcast signals are respectively specific to radio stations, and hence, plural radio stations existing respectively in different areas may use one equal broadcast frequency, in several cases. Therefore, radio broadcast stations cannot be identified merely depending on broadcast frequencies. Identification numbers called “call signs” assigned to broadcast stations are used.
In the information providing service described previously, for example, a service management server for managing the information providing service described above is provided together with another server which provides other related information such as programs and broadcasted songs of each broadcast station. The service management server includes a table which links broadcast frequencies, areas, and call signs to each other, and another table which links the call signs to URLs (Uniform Resource Locators) of information providing sites corresponding to the broadcast stations of the call signs.
To preset a broadcast frequency in an audio device, the broadcast frequency and information specifying the receiving area thereof (such as a postal code or the like) are transmitted to the service management server. According to this information and the like received, the service management server specifies the call sign of the broadcast station whose signal is being received by the audio device, and notifies the call sign to the audio device. In this manner, the broadcast frequency and the call sign can be stored linked to each other in the audio device.
Further, to attain information related to a program or the like, the user specifies a broadcast station by a preset number via the audio device, and then, a corresponding call sign is transmitted to the service management server. The service management server transmits the URL of the information providing site corresponding to the call sign, to the audio device. As a result of this, the audio device can have access to the URL and can be provided with information related to programs, broadcasted songs, and the like.
Note that there has been a conventional receiver capable of tuning accurately receivable broadcast channels. Of information concerning tuning and previously stored in a memory, the receiver stores into a preset memory such information that concerns tuning of broadcast channels receivable within an area chosen by a user, linked to tuning operation keys of a key operation unit which the user can operate. At this time, information items respectively concerning tunings of plural broadcast channels identified as broadcasting the same program are stored close to each other along a tuning-variable direction of the tuning operation keys (for example, see Patent Document 1).
Patent Document 1: Japanese Patent Application Laid-Open Publication No. 11-308135 (paragraph numbers [0041] to [0078], FIG. 1)
As described above, when presetting a broadcast frequency or a call sign, there can actually be a case that the call sign cannot be specified properly, in the method of specifying the call sign from information specifying an area such as a postal code and the reception frequency thereof. For example, if radio broadcast is received by a cable television set, a different frequency from the original broadcast frequency may be assigned by the cable television station. In some cases, cable television broadcasts a radio broadcast which originally cannot be received in an area because it is specific to another distant area. In these cases, the service management server as described above cannot specify the call sign corresponding to the reception frequency of such broadcast.